This Interagency Agreement is aimed at discovering the identity of genes involved in the birth defects known as neural tube defects (NTDs), the best known of which is spina bifida, and oral clefts. NICHD is collaborating with NHGRI to take advantage of NHGRI's expertise in genetic analysis. NICHD has been searching for risk factors for these defects for many years, and this search has recently focused on genetic variants that may predispose to these birth defects. NHGRI has the capability to do state of the art genetic analysis and has taken the responsibility for studying genetic factors associated with NTDs and clefts using samples provided by NICHD. NHGRI evaluates genetic variants to determine which are associated with NTDs or oral clefts. This will enable us and other investigators in the future to determine the functional effect, if any, of these changes in the biological code.